Vehicle seat control systems of this kind include those described below. Japanese Patent Application Publication No. 2003-2094 (JP-A-2003-2094) and Japanese Patent Application Publication No. 2003-532577 (JP-A-2003-532577) describe examples of devices in which the degree of support provided by side support portions of a vehicle seat is adjustable. In these examples, lateral acceleration that occurs when a vehicle turns a curve is estimated based on the curvature radius of the curve and the traveling speed of the vehicle, and the degree of support provided by the support portions of the driver's seat is adjusted based on the result of the estimation of the lateral acceleration.
Although, with the examples described in JP-A-2003-2094 and JP-A-2003-532577, it is possible to restrain an occupant by means of the side support portions of the vehicle seat when a vehicle turns a curve, there is a room for improvement in view of the purpose to restrain an occupant at a more proper time that the occupant feels appropriate.